If I was giving him maximum credit I'd guess that he got into some unhappiness with his publisher and for whatever reason isn't writing a new book until it gets sorted out.  Roc/Penguin probably owns all rights to Dresden as a novel, but he can get away with going to other publishers with graphic novels or selling Dresden merch b/c whatever contract they had probably sold rights to the novel series only.  Maybe even novels only for a period of time and hes trying to wait them out.  That would give him the benefit of the doubt on why he's supporting himself via comics, card games, and nic knacks for 5 years instead of writing a book.

If thats hot the case then well, hes probably just decided he has enough money that he can work 2 days a month by rambling at con panels then approving some junk to sell and not have to write anymore.  Which, TBH, has to be tempting if its an option.  I'm not sure i wouldn't take it if it was there.

I wish I had the kind of job where I could take a 3 or 4 year break from my paying work b/c of housing or family troubles and still have customers lined up waiting for me to return.

I've already decided that when the next book drops it will be the first one since I got into the series that will not be a day 1 buy for me.  I'll have waited at minimum 5 years for it at that point, another 1 or 2 won't matter.  Dresden files books are worth no more than about $3-4 to me at this point b/c I have no faith the series will ever be finished, plus they are a pain to read b/c I have to go back and recap if its going to be 4+ years in between every time.  The days of Dresden Files being worth a $20+ hardcover are done - and this right here, this 5 year gap, killed it.